Terahertz Radiation from Combined Metallic Slit Arrays

We report an approach to efficiently generate terahertz radiation from a combined periodic structure. The proposed configuration is composed of two metallic slit arrays deliberately designed with different periodic length, slit width and depth. We found that the combination of the two slit arrays could provide special electromagnetic modes, which exhibit nonradiative property above the surface of one slit array and radiative property inside the other one. An electron beam holding proper energy could resonate with those modes to generate strong and directional electromagnetic radiations in the terahertz regime, indicating that the approach has the potential in developing high-performance terahertz radiation sources

Space-Charge Limitation of a Femtosecond Photoinjector

Experimental investigation of a compact 40-kV diode-type photoelectric DC gun driven by 100 fs laser pulses revealed that the space-charge-limited current density could exceed 30 kA/cm2 and that the density increased linearly with the accelerating voltage. We explained these important properties by the balance between the cathode surface field and the field produced by sheet-like electron bunches near the cathode surface. Our simple physical model agreed well with the experimental results

Radiation Hybrid Maps of Medaka Chromosomes LG 12, 17, and 22

The Medaka is an excellent genetic system for studies of vertebrate development and disease and environmental and evolutionary biology studies. To facilitate the mapping of markers or the cloning of affected genes in Medaka mutants identified by forward-genetic screens, we have established a panel of whole-genome radiation hybrids (RHs) and RH maps for three Medaka chromosomes. RH mapping is useful, since markers to be mapped need not be polymorphic and one can establish the order of markers that are difficult to resolve by genetic mapping owing to low genetic recombination rates. RHs were generated by fusing the irradiated donor, OLF-136 Medaka cell line, with the host B78 mouse melanoma cells. Of 290 initial RH clones, we selected 93 on the basis of high retention of fragments of the Medaka genome to establish a panel that allows genotyping in the 96-well format. RH maps for linkage groups 12, 17, and 22 were generated using 159 markers. The average retention for the three chromosomes was 19% and the average break point frequency was ∼33 kb/cR. We estimate the potential resolution of the RH panel to be ∼186 kb, which is high enough for integrating RH data with bacterial artificial chromosome clones. Thus, this first RH panel will be a useful tool for mapping mutated genes in Medaka

Aggregation behavior of fluorooctanols in hydrocarbon solvents

金沢大学理工研究域物質化学系The association behaviors of three 1-octanols (1-octanol: C8OH; 1,1,2,2-tetrahydrotridecafluorooctanol TFC8OH; and 1,1-dihydropentadecafluorooctanol: DFC8OH) in two hydrocarbon solvents (n-hexane and benzene) were examined by vibration spectroscopy from 288.15 to 318.15 K. From the analysis of results with a mass action model, it was found that dimers and tetramers of 1-octanols coexisted with monomers in the n-hexane solution. These aggregates were formed by hydrogen bonding between the OH groups of 1-octanols. In the n-hexane solutions, an increase in the fluorination number of the 1-octanol molecule enhanced the intermolecular hydrogen bonding between the OH groups, but reduced the amounts of polymeric species. Conversely, in the benzene solution, the NIR experiment suggested that the OH groups of 1-octanols did not interact with other OH groups, but with the benzene molecules instead. It was found from 19F NMR chemical shift measurements that the fluorooctanols in the benzene solution aggregated by interaction between the fluorocarbon chains instead of by hydrogen bonding

二光束干渉計によるファブリー・ペローフリンジを利用した光学定数測定

A Fourier spectrometer is usually used for the measurement of optical properties of various kind of infrared materials because of its brightness and high resolution. In this note a method is explained, by referring the literatures, for analyzing Fabry-Perot fringes in Fourier spectroscopy to determine optical constants of infrared material

Ceramic Pressure-Tight Housings for Ocean-Bottom Seismometers Applicable to 11-km Water Depth

Ceramics have some outstanding features that are necessary for pressure-tight housings, such as higher compressive strength, lower specific gravity, and higher resistance against corrosion. One promising application is pressure-tight housings for a free-fall popup ocean-bottom seismometer (OBS). Ceramic pressure-tight housings can provide sufficient strength and buoyancy even at 11-km water depth. Nevertheless, tensile and bending strengths of ceramics are only a fraction of their compressive strength. For metals, they are almost equal. Therefore, common design methods for pressure-tight housings are not directly applicable to ceramic pressure-tight housings. As described herein, we propose a new design method for ceramic pressure-tight housings, particularly a method of reinforcement of through-holes for underwater connectors. We also present detailed data that support the proposed design method

Aggregatibacter actinomycetemcomitans Omp29 Is Associated with Bacterial Entry to Gingival Epithelial Cells by F-Actin Rearrangement

The onset and progressive pathogenesis of periodontal disease is thought to be initiated by the entry of Aggregatibacter actinomycetemcomitans (Aa) into periodontal tissue, especially gingival epithelium. Nonetheless, the mechanism underlying such bacterial entry remains to be clarified. Therefore, this study aimed to investigate the possible role of Aa outer membrane protein 29 kD (Omp29), a homologue of E. coli OmpA, in promoting bacterial entry into gingival epithelial cells. To accomplish this, Omp29 expression vector was incorporated in an OmpA-deficient mutant of E. coli. Omp29+/OmpA− E. coli demonstrated 22-fold higher entry into human gingival epithelial line cells (OBA9) than Omp29−/OmpA− E. coli. While the entry of Aa and Omp29+/OmpA− E. coli into OBA9 cells were inhibited by anti-Omp29 antibody, their adherence to OBA9 cells was not inhibited. Stimulation of OBA9 cells with purified Omp29 increased the phosphorylation of focal adhesion kinase (FAK), a pivotal cell-signaling molecule that can up-regulate actin rearrangement. Furthermore, Omp29 increased the formation of F-actin in OBA9 cells. The internalization of Omp29-coated beads and the entry of Aa into OBA9 were partially inhibited by treatment with PI3-kinase inhibitor (Wortmannin) and Rho GTPases inhibitor (EDIN), both known to convey FAK-signaling to actin-rearrangement. These results suggest that Omp29 is associated with the entry of Aa into gingival epithelial cells by up-regulating F-actin rearrangement via the FAK signaling pathway

Characteristic Metabolism of Free Amino Acids in Cetacean Plasma: Cluster Analysis and Comparison with Mice

From an evolutionary perspective, the ancestors of cetaceans first lived in terrestrial environments prior to adapting to aquatic environments. Whereas anatomical and morphological adaptations to aquatic environments have been well studied, few studies have focused on physiological changes. We focused on plasma amino acid concentrations (aminograms) since they show distinct patterns under various physiological conditions. Plasma and urine aminograms were obtained from bottlenose dolphins, pacific white-sided dolphins, Risso's dolphins, false-killer whales and C57BL/6J and ICR mice. Hierarchical cluster analyses were employed to uncover a multitude of amino acid relationships among different species, which can help us understand the complex interrelations comprising metabolic adaptations. The cetacean aminograms formed a cluster that was markedly distinguishable from the mouse cluster, indicating that cetaceans and terrestrial mammals have quite different metabolic machinery for amino acids. Levels of carnosine and 3-methylhistidine, both of which are antioxidants, were substantially higher in cetaceans. Urea was markedly elevated in cetaceans, whereas the level of urea cycle-related amino acids was lower. Because diving mammals must cope with high rates of reactive oxygen species generation due to alterations in apnea/reoxygenation and ischemia-reperfusion processes, high concentrations of antioxidative amino acids are advantageous. Moreover, shifting the set point of urea cycle may be an adaption used for body water conservation in the hyperosmotic sea water environment, because urea functions as a major blood osmolyte. Furthermore, since dolphins are kept in many aquariums for observation, the evaluation of these aminograms may provide useful diagnostic indices for the assessment of cetacean health in artificial environments in the future